Adding this code in the Global Sentora Entry works perfect for me:
It allows every domain acces webmail trough webmail.domain.tls
Code:
</VirtualHost>
# Configuration for WebMail
<VirtualHost *:80>
ServerAlias webmail.*
DocumentRoot "/etc/sentora/panel/etc/apps/webmail/"
AddType application/x-httpd-php .php
<Directory "/etc/sentora/panel/etc/apps/webmail/">
Options +FollowSymLinks -Indexes
AllowOverride All
Require all granted
</Directory>
It allows every domain acces webmail trough webmail.domain.tls